23 2 CLOUDS AND FOG Clouds Small water

23 -2 CLOUDS AND FOG

Clouds �Small water droplets or ice crystals that fall through air �Fog is a cloud that forms near the surface

Formation �Solid surface are needed for water vapor to condense on �Troposphere – lower layer of atmosphere �Ice, salt, dust – remain suspended in the air for a long time

�Condensation nuclei – particles for water vapor to condense on �Water droplets form �Cooling air causes the condensation

Adiabatic Cooling �Temperature of an air mass decreases as the air mass rises and expands

Mixing �Moist air mixes with another body of moist air with different temperatures

Lifting �Sloping terrain forces air up �Rising air expands and cools

Advective Cooling �Temperature of an air mass decreases as it moves over a cold surface

Classifications of Clouds �Shape and altitude

Cloud Types � 3 Main Cloud Types (Based on Appearance) Cirrus - Wispy, Feather-like clouds Cumulus – Fluffy, Cotton ball-like clouds Stratus – Layered, Sheet-like clouds

Stratus �Gray �Flat, uniform base �Low altitudes

Cumulus �Top – cotton ball �Bottom – dark �Low level �Billowy

Cirrus �Feathery �Ice crystals �High altitude

Cloud Types �Cloud Prefixes - Determines Cloud Subtypes Cirro – High Elevation Alto – Medium Elevation Strato – Layered Nimbo – Rain � Ex: An altocumulus cloud is a medium elevation cumulus cloud

Rain Clouds �Cumulonimbus – Large, anvil-shaped storm clouds associated with storms and hail �Nimbostratus – Dark, layered rain clouds

Fog �Water vapor that has condensed by Earth’s surface

Radiation Fog �Nightly �Layer of air in contact with ground cools below dew point �Results from loss of heat due to radiation